Abstract Primary brain tumors (PBT) are rare, accounting for less than 2% of all cancers, present acutely, and often require specialized care to determine treatment approaches. Neuro-Oncology clinics are located in densely populated urban areas resulting in additional access barriers, such as longer travel time, for those in non-urban areas. To better understand how proximity to our facility affects patient outcomes among PBT patients enrolled in the National Institutes of Health (NIH) Natural History Study (NCT02851706, PI: Armstrong), we assessed the association of population density with symptom duration before diagnosis, time to first treatment, and overall survival among a cohort of 666 adult PBT patients. More urbanized areas were defined as areas with a core population density of more than 1,000 persons per square mile. T-tests and chi-squared tests were performed to assess differences in patient and tumor characteristics based on population density (more urbanized vs. less urbanized). We used ordinal logistic regression (odds ratio [OR], 95% confidence intervals [CI]) to assess the association between duration of presenting symptoms (<6 months, 6 months-1 year, ≥1 year) and linear regression (beta coefficient, 95% CI) for time to treatment and population density. We adjusted for age at cancer diagnosis and sex (male, female), and results were stratified according to residential distance to the NIH (short distance=<200 miles, long distance=200+ miles), to control for local referral patterns. Kaplan-Meier estimates were used to assess overall survival by population density levels, overall, and by residential distance. All models were then further stratified by tumor grade (low, high). Among 666 patients diagnosed with PBTs, 401 (60%) lived in more urbanized areas, 40% were long distance, and 24% had low-grade tumors. Patients living in more urbanized areas were more racially diverse (p<0.001), had higher educational attainment (p<0.001), and were more likely to be single (p=0.008). In the overall cohort and when stratified by distance to NIH or tumor grade, there were no associations between population density level and symptom duration prior to diagnosis. Time to treatment for radiation and chemotherapy was longer for PBT patients living in less urbanized areas and longer distances from the NIH (β=0.63; 95%CI=0.08,1.17) compared to those living in more urbanized areas. There were no differences in the 5-year survival rates between more or less urbanized groups. In conclusion, access to care for those in less urbanized areas was demonstrated, although survival was not impacted. Future consideration should be given to novel approaches to increase access to specialized care, particularly for PBT patients living further from urban areas. Citation Format: Macy L. Stockdill, Jacqueline B. Vo, Orieta Celiku, Zuena Karim, Yeonju Kim, Hope Miller, Elizabeth Vera, Terri S. Armstrong. The impact of urban residence on symptom duration, treatment initiation, and survival among primary brain tumor patients: A large cohort analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2155.

Abstract BACKGROUND Barriers to clinical trial access have significant implications for patient care and disproportionally impact rural and socioeconomically disadvantaged populations. Expanding on reported disparities in neuro-oncology trial availability, we assessed whether existing networks of clinical providers and collaboratives, including NCI’s National Clinical Trials Network (NCTN) and Community Oncology Research Program (NCORP), can effectively bridge these disparities. METHODS Locations of adult neuro-oncology trial sites, UCNS-certified neuro-oncologists, NCTN Main Members, NCORP Community Affiliates, and general oncologists reporting to Centers for Medicare/Medicaid Services were obtained, mapped to zip code tabulation areas (ZCTAs), and annotated with US Census population and geography data and the Neighborhood Atlas Area Deprivation Index (ADI). Regression and spatial analyses were conducted assessing the role of geography, socioeconomic disadvantage, and population on infrastructure accessibility. RESULTS We identified 1976 neuro-oncology trials, 586 NCTN institutions, 962 NCORP sites, 306 neuro-oncologists, and 863 general oncologists located in just 8% of all ZCTAs, inhabited by 19% of the US population. All trial-supporting infrastructure components were more likely to exist in more populated, geographically neighboring regions (OR >1, p< 0.00001). Trial sites, NCTN institutions, and neuro-oncologists served ZCTAs with less disadvantage (OR=0.99, p=0.03958; OR=0.99, p< 0.00001; OR=0.98, p< 0.00001), while NCORP served more disadvantaged areas (OR=1.01, p=0.00102) and general oncologists were distributed similarly across ADI (OR=1.00, p=0.94317). Investigating potentially underutilized infrastructure, 2 neuro-oncologists, 8 NCTN institutions, 10 NCORP sites, and 107 general oncologists were located more than 25 miles from utilized trial sites. CONCLUSION The identified disparities in neuro-oncologists and trial-supporting institutions reflect disparities in trial-site access and point to broader disparities in neuro-oncology care access. NCORP sites reach more socioeconomically disadvantaged populations, but the overall sparsity of trial-supporting networks indicates that the existing infrastructure cannot effectively bridge trial-access barriers and novel approaches including telehealth and decentralized trial designs may be necessary to promote equity.